Oarisma poweshiek

(Parker, 1870)

Poweshiek Skipperling

The Poweshiek skipperling is a small, critically endangered North grass . Historically common across tallgrass prairie systems of the upper Midwest United States and southern Manitoba, Canada, it has experienced catastrophic declines since 2005. The now persists at only six verified extant sites: four prairie fens in Michigan, one mesic prairie in Wisconsin, and one tallgrass prairie in Manitoba. Intensive efforts include captive breeding programs at the Minnesota Zoo and Assiniboine Park Conservancy, federal protection in both countries, and restoration initiatives.

Oarisma poweshiek by Northern Prairie Wildlife Research Center - USGS. Used under a Public domain license.

Annual report on the noxious, beneficial and other insects of the State of Missouri (1869) (19372434621) by Internet Archive Book Images. Used under a No restrictions license.

Pronunciation

How to pronounce Oarisma poweshiek: /oʊˈæɹɪzmə ˈpaʊʃiːk/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from similar grass by combination of small size (24–30 mm wingspan), dark upperside with orange restricted to , and dark grey underside with conspicuous . Distinguished from western Oarisma garita by geographic range and subtle pattern differences; misidentifications have occurred in historical records.

Images

Appearance

Small with wingspan of 24–30 mm. Upperside dark with orange along the . Underside of dark grey with .

Habitat

Tallgrass prairie and prairie fen . In Michigan, occupies prairie fens with open vegetation structure and abundant nectar sources, particularly Dasiphora fruticosa. In Manitoba, uses tallgrass prairie with microhabitats distributed along soil moisture gradients: -laying associated with mesic sections, resting/basking with drier sections, and nectar feeding across the gradient. Occupied sites characterized by early successional prairie conditions maintained by disturbance.

Distribution

Historic range: ten U.S. states (Illinois, Indiana, Iowa, Michigan, Minnesota, Nebraska, North Dakota, Ohio, South Dakota, Wisconsin) and southeastern Manitoba, Canada. Current range reduced to approximately 1% of historic extent; six extant at range margins: four in Michigan prairie fens, one in Wisconsin mesic prairie, and one in Manitoba tallgrass prairie. Previously unknown records from Nebraska and Ohio discovered through occurrence data .

Seasonality

with period from late June to mid-July. Adult lifespan approximately two weeks. Exact timing varies with weather conditions; warm early springs favor earlier .

Diet

nectar on flowers; females most frequently observed on Dasiphora fruticosa, males most often on Rudbeckia hirta. feed on graminoid plants including Andropogon gerardi, Muhlenbergia richardsonis, Muhlenbergia glomerata, Sporobolus heterolepis, Schizachyrium scoparium, and Carex sterilis, alternating between throughout development.

Host Associations

Andropogon gerardi - larval Poaceae, big bluestem
Muhlenbergia richardsonis - larval Poaceae; documented site
Muhlenbergia glomerata - larval Poaceae; documented site
Sporobolus heterolepis - larval Poaceae, prairie dropseed
Schizachyrium scoparium - larval Poaceae, little bluestem; also indicator of occupied sites
Carex sterilis - larval Cyperaceae; documented site
Dasiphora fruticosa - nectar sourceRosaceae, shrubby cinquefoil; primary nectar for females, also site
Rudbeckia hirta - nectar sourceAsteraceae, black-eyed Susan; primary nectar for males, strong predictor of abundance in Manitoba

Life Cycle

(one per year). laid on plants in mid-summer. feed on graminoid shoots, navigating microhabitats to locate host plants and alternating between throughout development. Larvae likely enter as partially grown individuals, in prairie vegetation. occurs in spring; eclose in late June to mid-July. Development sensitive to temperature: accumulation from egg hatch to eclosure similar to O. garita, but with lower variability suggesting reduced to climate change.

Behavior

exhibit activity patterns distributed along soil moisture gradients: -laying concentrated in mesic areas, resting and basking in drier areas, nectar feeding across moisture conditions. Adults almost exclusively within prairie , rarely in shrub or ephemeral wetland communities, never observed in wetland or forest. navigate microhabitats to locate plants, demonstrating active foraging . Breeding behaviors in captivity positively associated with sunlight intensity, negatively associated with adult age; no detected effect of ambient temperature on breeding behavior frequency.

Ecological Role

of prairie wildflowers, particularly Dasiphora fruticosa and Rudbeckia hirta. of prairie grasses and sedges. Serves as for high-quality tallgrass prairie and prairie fen . Poor disperser with limited long-distance movement capability.

Human Relevance

Subject of intensive efforts due to endangered status. Federally endangered in United States (2014) and Canada (SARA endangered status 2019). Captive breeding programs at Minnesota Zoo and Assiniboine Park Conservancy have released over 800 individuals combined. use limitation areas established by EPA to protect remaining . Research subject for studies on prairie management effects, climate change sensitivity, and conservation genetics. Named for Iowa county of Poweshiek.

Similar Taxa

Oarisma garitaWestern with overlapping morphological features; distinguished by geographic range and greater developmental variability suggesting higher climate

More Details

Conservation Status Timeline

NatureServe G1 (critically imperiled); US ESA endangered 2014; COSEWIC threatened 2003, endangered 2014; Canada SARA threatened 2005, endangered 2019. crash occurred between 2005–2015 after being historically common.

Captive Breeding Achievements

Minnesota Zoo initiated captive rearing in 2018, releasing over 100 individuals in 2022. Assiniboine Park Conservancy Grassland Program released over 700 individuals and completed first reintroduction at extirpated site.

Management Sensitivity

Abundance negatively associated with years since burning or grazing, indicating need for regular disturbance to maintain early successional . However, widespread adoption of prescribed burning correlated with regional declines, suggesting complex management trade-offs. Cumulative May–June precipitation negatively affects abundance; warm early springs and cool temperatures during active period have positive effects.

Genetic Considerations

Historical was high across the range despite poor ability, facilitated by formerly widespread prairie . Current weakly differentiated genetically but with low diversity, informing reintroduction strategies to maintain gene flow networks.